Apparatus for securing threaded members and for detecting improperly secured threaded members



May 3, 1966 J KENNEDY ETAL APPARATUS FOR SECURING THREADED MEMBERS AND FOR D IMPROPERLY SECURED THREADED MEMBERS 3,249,221 ETECTING Filed June 22, 1964 u s v.

\NVENTOES J..J.I ENNEDV L LA. POJMAN ATTOENEY APPARATUS FOR SECURING THREADED MEM- BERS AND FOR DETECTING IMPROPERLY SE- CURED THREADED MEMBERS John J. Kennedy, Riverside, and Louis A. Pojman, Cream,

11]., assignors to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed June 22, 1964, Ser. No. 376,830 6 Claims. (Cl. 209-74) The present invention relates generally to apparatus for securing threaded members to articles and for automatically determining the securement thereof, and more particularly to apparatus for tightening threaded members in articles and for automatically rejecting articles in which the threaded members have not been tightened to whether or not the screws were tightened'to the pre-' scribed torque; hence it the screw driver broke or failed to enter the-notch in the screw, or if the threads of the screw or the receiving element were stripped, the entire relay was defective, but was nonetheless transferred un detected to a testing or storage area.

Accordingly, a general object of the invention is to provide new and improved apparatus for securing threaded members to articles and for automatically rejecting articles with improperly secured threaded members, and more particularly to provide new and improved apparatus for tightening threaded members in articles to a prescribed torque and for automatically rejecting articles in which the threaded members have not been tightened to the prescribed torque. another object of the invention is to provide in an automatic assembly line wherein threaded members are tightened in an article to a prescribed torque by a fluid-driven device, a system for detecting whether or not the threaded members have been tightened to the prescribed torque and for automatically rejecting those articles in which the threaded members have not been so tightened.

A further object of the invention is to provide a detecting and rejecting system in accordance with the preceding object, which system capitalizes upon the inherent characteristics of the fluid-driven tightening device-namely, the development of a surge in the pressure within the fluid-supply system when a prescribed stalling torque is reached-40 determine whether or not the threaded member has been tightened in the article to the prescribed torque so that associated mechanism may be actuated accordingly to accept or reject the article.

A still further object of the invention is to provide new and improved apparatus for tightening threaded members in articles and for rejecting articles in which the threaded members have not been properly tightened, wherein the operation of such apparatus is completely automatic so that an article may be assembled along an automatic assembly line, wherein the apparatus features a fail-safe system of rejecting articles bearing improperly tightened threaded members and wherein the apparatus is simple in construction and efiicient in operation.

Apparatus accomplishing the above objects and advantages in accordance with the invention, includes the combination with a conveyor system for advancing articles 'each having a threaded member started therein--and a v United States Patent moved from the conveyor subsequent to the tightening operation, and so that articles in which the threaded members have been tightened to the prescribed torque are permitted to continue advancing along the conveyor.

In accordance with a preferred embodiment of the invention, apparatus is provided for tightening threaded members in articles and for automatically rejecting articles in which the threaded members have not been tightened to a prescribed torque. Such apparatus includes a con- .veyor system for advancing articles having threaded members started therein and fluid-driven devices for tightening the threaded members in the articles, the fluid-driven devices including a fluid-supply system in which a surge in pressure results when a prescribed stalling torque is reached.

A device is arranged in the the fluid-supply system of each tightening device to respond to such surge in pressure by actuating auxiliary mechanism to remove a deflector normally positioned to deflect advancing articles from the conveyor system subsequent to the tightening operation. Additional mechanism is responsive to advancement of an article along the conveyor system beyond the deflector to return the deflector to its normal position. Thus, articles in which the threaded members have been tightened to the prescribed torque are advanced undefiected along the conveyor system, whereas articles in which the threaded members have not been tightened to the prescribed torque are deflected from the conveyor system as rejects.

Other objects, advantages and aspects of the invention will become apparent from the following detailed description of the specific embodiment thereof when taken in conjunction with the appended drawing in which:

FIG. 1 is an electro-mechanical, diagrammatic elevational View of apparatus forming a preferred embodiment of the invention, and

FIG. 2 is an electro-mechanical, diagrammatic plan view of'the apparatus in FIG. 1, with portions removed for purposes of clarity.

In the manufacture of step-by-step relays for communication systems, the relays are assembled along an automatic assembly line. The various component parts are first loosely stacked to form a relay pile-up and screws for securing the pile-up to the relay armature are started therein. As shown-in FIG. 2, such a relay pile-up 10 is assembled in a carrier 11 which is fed -on.a driven belt conveyor 12 to a tightening station where the carrier 11 engages a stop 13 on a work table 14. A conventional timing mechanism 16 energizes a solenoid valve 17 through a conductor A to actuate an air cylinder 18 to move the carrier 11 laterally of itself until it engages a stop 19 on the work table 14. The timing mechanism 16 then deenergizes the solenoid valve 17, which automatically reverses the same to return the cylinder 18 to its initial condition, and energizes a solenoid valve 21 through a conductor B to actuate an air cylinder 22 .to advance the carrier 11 until it engages a removable stop 23 projecting upward through a bore 24 (FIG. 1) in the Work table 14 to a height sufiicient to stop the carrier 11.

With the carrier 11 held firmly in place between a Patented May 3, 1966' nism 16 deenergizes the solenoid valve 21 without reversing it so that the plunger 26 continues to hold the carrier 11 against the removable stop 23. In this position, a pair of prestarted screws 27-27 are automatically tightened to a prescribed torque. The timing mechanism 16 commences the tightening operation by energizing a pair of solenoid valves 28-28 (FIG. 1) through conductors C and D to actuate associated air cylinders 29-29 secured to a movable platform 31 to extend plungers 32-32 therein which are pendantly mounted from a stationary platform 33 and thereby to lower the movable platform 31 on a plurality of guide standards 34-34.

As the movable platform 31 is lower-ed, a pair of rotating screw drivers 36-36, mounted in a guide bracket 37 depending from the movable platform 31 and aligned with the screws 27-27 in the pile-up 111, are engaged with the heads of the screws. Each screw driver 36 is springloaded (not shown) so that it yields slightly when engaged with the head of the corresponding screw 27. In this manner, the spring pressure forces the tip of the rotating screw driver 36 into the notch in the head of the screw 26 when it becomes aligned therewith, and the screw 27 is then tightened in the pile-up 113 by the rotating screw driver 36.

After a selected duration of the tightening operation, the timing mechanism deenergizes the solenoid valves 28-28 to reverse the same, thereby actuating the air cylinders 29-29 to retract the plungers 32-32 and elevate the movable platform 31. At the same time, the timing mechanism 16 energizes a. solenoid valve 38 (FIG. 1) through a conductor E to actuate an air cylinder 39 to retract the removable stop 23, and again energizes the solenoid valve 21. (FIG. 2) to actuate the air cylinder 22 to advance the carrier 11 onto a second driven belt conveyor 41 for removal to a testing or storage area.

Thus fan-the tightening operation as described constitutes the manner in which threaded members have heretofore been tightened to complete the assembly of step-by-steprelays. The pneumatic control system for the various solenoid valves and air cylinders is conventional and is not shown-its ramifications being Well understood by those skilled in the art.

It is apparent, however, that the automatic tightening apparatus as described, makes no provision for detecting relays in which the threaded members have not been tightened to the prescribed torque, and hence such relays nonetheless continue along the automatic assembly line undetected. This might occur as the result of several factors-for example, the screw drivers 36-36 may have been broken or may not have entered the notches in the screws, or the threads of the screw or the receiving socket in the relay may have been stripped. In order to overcome this problem, a detection system was developed.

which capitalizes upon the inherent operation and characteristics of air motors 42-42 which drive the screw drivers 36-36, to detect an improperly secured threaded member. Since the detection system is dependent upon the air motors 42-42 and the supply system therefor, such pneumatic system will be described in detail below with reference to FIG. 1.

The air motors 42-42 are of the type which may be adjusted in a manner well known in the art to stall when a prescribed resistance torque is reached. The air motors 42-42 are mounted on the stationary platform 33 and are connected through a pair of flexible shafts 43-43 to the screw drivers 36-36. The pneumatic supply system for the motors 42-42 includes a pump (not shown) for supplying air to a conduit 44 at approximately 90 p.s.i. A valve 46 arranged in the conduit 44 is adjusted to reduce the pressure to 70 p.s.i. and a pair of valves 47-47, each arranged in a branch conduit 48 connecting the main conduit 44-to one of the air motors 42-42, reduce the pressure further to 40 p.s.i.-the normal drive pressure for the motors 42-42.

An inherent characteristic in the operation of such air motors 42-42 is that a surge in the pressure within the supply system for the motors 42-42 accompanies the reaching of the prescribed stalling torque. In the particular system shown in FIG. 1, this surge causes an increase in the pressure within the branch conduits 48-48 of approximately to p.s.i. above the normal driving pressure of the motor. As a result, the pressure is increased from p.s.i. to or 50 p.s.i. by the surge, a change which is readily detectable and hence may be utilized to determine whether or not the screws 27-27 have been tightened to the prescribed torque-the absence of such surge indicating that the motors 42-42 never reached the prescribed stalling torque.

To sense whether or not such a surge has in fact occurred during the tightening operation, a pair of air cylinders 51-51 are arranged one in each of the branch conduits 48-48 and are calibrated such thata threshold pressure of 45 p.s.i; is required to force a plunger 52 outward in each cylinder 51 to close a normally open microswitch 53. The cylinders 51-51 are calibrated by means of a calibrated spring 54 mounted within each cylinder 51 to bias the plunger 52 to a normal position in which the microswitch 53 isheld open, the spring being calibrated to be overcome by a pressure of approximately 45 p.s.i. to permit the plunger 52 to close the microswitch 53 and complete a circuit therethrough.

Each of the microswitches 53-53 are connectedin series through a conductor F to a transformer 56, and if both are closed by the respective plungers 52-52, a circult is completed through the conductor F to energize a solenoid valve 5'7 (FIG. 2) to actuate an air cylinder 58 and retract a plunger 59 therein to control a deflector or gate 61. The air cylinder 58 is secured to the bed of the belt conveyor 41 and the plunger 59 is pivotably attached at its remote end to the gate 61 which in turn is pivotably mounted on the bed of the conveyor 41. The plunger 59 is normally extended in the cylinder 58 so that the gate 61 extends across the conveyor 41 to deflect carriers 11-11 being advanced from the. tightening station into an inclined chute 62 which deposits the carrier 11 and pile-up, 111 at a station for rejects.

Upon energization of the solenoid valve 57, the plunger 59 is retracted in the cylinder 58 to pivot the gate 61 out of the path of an advancing carrier 11 sothat the carrier continues advancing along the conveyor 41 undeflected. Thus, in the absence of a surge in pressure during the tightening operation for either of the air motors 42-42, indicating that the prescribed torque was not reached, the corresponding microswitch 54 is not closed and the gate 61 remains in the path of the carrier 11 as it is advanced from the tightening operation by the conveyor 41 to deflect it into the inclined chute 62 for deposit at the reject station.

If, however, boih of the motors 42-42 reach the prescribed stalling torque the resulting surge in pressure in the fluid supply system overcomes the calibrated springs 54-54 in the air cylinders 51-51 to close the microswitches 53-53, thus energizing the solenoid valve 57 to remove the gate 61 from the path of the carrier 11 and it passes undeflected.

After the carrier 11 has been advanced beyond the gate 61 by the conveyor 41, it engages a pivotable arm 63 and pivots the arm out of its path, which pivotal movement closes a normally open microswitch 64 to complete an energizing circuit through a conductor G from the transformer 56 to the solenoid valve 57 to reverse it and cause the air cylinder 58 to extend the plunger 59 and reposition the gate 61 across the conveyor 41.

It is apparent, therefore, that if either of the air motors 42-42 fail to reach the stalling torque, indicating that the screws. 27-27 have not been tightened to the prescribed torque, the gate 61 will not be removed from across the conveyor 41 and the deflective relay 16 will be deflected into the inclined chute 62 and deposited at the reject station. However, if both of the air motors 42-42 stall at the prescribed torque, the gate 61 is removed from the path of the advancing carrier 11 and it proceeds along the .conveyor 41 undeflected. When the carrier 11 passes the gate 61, the pivotal arm 63 closes the microswitch 64 to reverse the solenoid valve 57 and to reposition the gate 61'across the conveyor 41. Hence, a failsafe system is provided in which only those relays having screws properly tightened to the prescribed troque will be permitted to continue advancing along the conveyor 41.

While one specific embodiment of the invention is described in detail hereinabove, various modifications may be made without departing from the spirit and scope of the invention, and it is intended that all such modifications be considered as contemplated by the invention. What is claimedis: 1. Apparatus for securing threaded members to articles and for automatically rejecting articles with improperly secured threaded members, which apparatus comprises: a conveyor for advancing articles one at a time with the threaded members partially secured thereto to and from a tightening station; fluid-driven means arranged at the tightening station for securing the threaded membersto the articles and including a fluid-supply system, said securing means being adjustable to stall at a prescribed torque with a resultant surge in the pressure within the fluidsupply system, the articles being automatically advanced away from the tightening station by said conveyor after the securing operation; and means responsive to the pressure in the fluid-supply system of said securing means, for removing articles from said conveyor as the articles are advanced away from the tightening station by said conveyor subsequent to the securing .operation if the pressure in the fluid-supply system remains substantially constant during the securing operation for such articles, the absence ofa surge in pressure indicating that the prescribed torque was not reached and that the' threaded members were improperly secured.

2. The apparatus as recited in claim 1, wherein the article-removing means comprise:

removable means for deflecting advancing articles from the conveyor subsequent to the securing operation; and means responsive to a prescribed surge in the pressure within the fluid-supply system for the securing means, to remove said article-deflecting means from the path of an advancing article, whereby articles for which the, prescribed torque was not reached are detected by the absence of a surge in pressure in the fluid-supply system and the article-deflecting means deflects such articles from the conveyor. 3. In combination with a conveyor system for advancing articles to and from a tightening station, each article having a threaded member started therein, and a fluidening the threaded members in the articles, which device stalls when a prescribed torque is reached causing a surge in the pressure within the fluid-supply system therefor, the improvement comprising:

means for removing advancing articles from the conveyor subsequent to the tightening operation; and means for monitoring the pressure within thefluiddriven device arranged at the tightening station for tightstation, the articles being automatically advanced away from the tightening station by said conveyor system after the tightening operation;

means for supplying fluid under pressure to drive said tightening means, said tightening means being adjustable to stall when a prescribed torque is reached .causing a corresponding surge in the pressure Within said fluid-supply means;

removable deflector means arranged along said conveyor system subsequent to the tightening station and normally positioned to deflect advancing articles from said conveyor system;

means energizeable to remove said deflector means from the path of advancing articles;

means arranged in said fluid-supply means and responsive to the surge in pressure caused when the prescribed stalling torque hasbeen reached, to energize said removing means to remove said deflector means from the path of advancing articles; and

means responsive to the advancement of an article along said conveyor system beyond said deflector means to return said deflector means to the normal position therefor;

whereby articles in which the threaded members have been tightened to the prescribed torque are advanced undeflected along said conveyor system, whereas articles in which the threaded members have not been tightened to the prescribed torque are deflected from the conveyor system as rejects.

5. In combination with a conveyor system for advancing articles to and from a tightening station, each article having a threaded member started therein, and a fluiddriven device arranged at the tightening station for tightening the threaded members in the articles, which device stalls When a prescribed torque is reached causing a surge in the pressure Within the fluid-supply system therefor, the improvement comprising:

means for removing advancing articles from the conveyor subsequent to the tightening operation;

means energizable to disable the article-removing means from removing articles from the conveyor system;

- means for monitoring the pressure within the fluidsupply system and for detecting a surge in pressure therein; means responsive to the detection by said monitoring and detecting means of a surge in the pressure Within the fluid system which results when the predetermined torque is reached to energize said disabling means; and

means responsive to advancement of an article beyond the article-removing means along the conveyor systern, to rehabilitate said article-removing means so that the same may remove articles from the conveyor system.

6. Apparatus for tightening a plurality of threaded members in each of a succession of articles and for automatically rejecting articles in which all of the plurality of threaded members have not been tightened to a prescribed torque, which apparatus comprises:

means for independently supplying fluid under pres- I sure to each of said plurality of tightening means, each of said tightening means being adjustable to stall When a prescribed torque is reached causing a corresponding surge within its associated fluid-supply means;

removable deflector means arranged along said conveyor system subsequent to the tightening station and normally positioned to deflect advancing articles from said conveyor system;

means energizable to remove said deflector means from the path of advancing articles;

actuatable control means arranged in each of said independent fluid-supply means and responsive to the surge in pressure caused therein when said associated tightening means has reached the prescribed stalling torque;

means responsive to said actuatable control means upon the occurrence of a surge of pressure within each of said independent fluid-supply means associated with the plurality of fluid-driven means, to energize said removing means to remove said deflector means from the path of advancing articles; and

means responsive to the advancement of an article along said conveyor system beyond said deflector means to return said deflector means to the normal position therefor;

whereby articles in which all of the threaded-members have been tightened to the prescribed torque are advanced undeflected along said conveyor system,

v whereas articles in which all of the threaded members have not been tightened to the prescri bed torque are deflected from the conveyor system as rejects.

References Cited by the Examiner UNITED STATES PATENTS 2,415,552 2/1947 Broecker 29 '240 2,833,321 5/1958 Hautau 144 32 2,943,335 7/1960 Daniel 209 s2x References Cited by the Applicant UNITED STATES PATENT 2,627,770 2/1953 Hautau. 2,880,770 4/1959 Ettinger.

M. HENSON WOOD, JR., Primary Examiner.

J N. ERLICH, Assistant Examiner. 

1. APPARATUS FOR SECURING THREADED MEMBERS TO ARTICLES AND FOR AUTOMATICALLY REJECTING ARTICLES WITH IMPROPERLY SECURED THREADED MEMBERS, WHICH APPARATUS COMPRISES: A CONVEYOR FOR ADVANCING ARTICLES ONE AT A TIME WITH THE THREADED MEMBERS PARTIALLY SECURED THERETO TO AND FROM A TIGHTENING STATION; FLUID-DRIVEN MEANS ARRANGED AT THE TIGHTENING STATION FOR SECURING THE THREADED MEMBERS TO THE ARTICLES AND INCLUDING A FLUID-SUPPLY SYSTEM, SAID SECURING MEANS BEING ADJUSTABLE TO STALL AT A PRESCRIBED TORQUE WITH A RESULTANT SURGE IN THE PRESSURE WITHIN THE FLUIDSUPPLY SYSTEM, THE ARTICLES BEING AUTOMATICALLY ADVANCED AWAY FROM THE TIGHTENING STATION BY SAID CONVEYOR AFTER THE SECURING OPERATION; AND MEANS RESPONSIVE TO THE PRESSURE IN THE FLUID-SUPPLY 